The present invention relates to new and useful improvements in electric resistance heating elements, particularly of the cartridge type. The following U.S. patents afford an understanding of the prior art as presently known by applicant:
______________________________________ 2 831 951 Desloge Apr 22, 1958 2 977 453 Wells Mar 28, 1961 3 134 956 Boggs May 26, 1964 3 219 279 Boggs Nov 9, 1965 3 307 135 Simmons Feb 28, 1967 3 812 580 Drugmand May 28, 1974 ______________________________________
My invention distinguishes from the above in that it provides for energization of separate circuits within the cartridge element, through use of one voltage source to energize one coil, and a different voltage source to energize the other coil. For example, one voltage may be 120 volts whereas the other may be 12 volts. Establishment of separate circuits of different voltages is made possible by electrically connecting the heating coils so that two each have one end in common connection with one terminal, and the other ends of the coils have connection with respective second and third terminals.